A cerebral ischemic disease is a disorder where necessary blood flow is not supplied to the brain due to thrombus, atherosclerosis, etc. which occurs when blood vessel is obstructed for some reasons, and said ischemic diseases include, for example, cerebral infarction, cerebral hemorrhage, subarachnoid hemmorhage and white matter disorders.
At present, blood flow-improving agents, cerebral metabolism activators, radical scavengers, etc. are used for the treatment of cerebral ischemic diseases. For example, in case of cerebral infarction, the disease can be treated by dissolving generated thrombus and restoring the blood flow again. A thrombolytic agent is usually used for dissolving generated thrombus. As the thrombolytic agent, there has been used tissue plasminogen activator (hereinafter abbreviated as t-PA), urobilinogen (urokinase) and the like (N. Engl. J. Med., 333, 1581 (1995)). However, administration of such thrombolytic agent, particularly t-PA is restricted within 3 hours after occurrence of ischemia, because adverse effects such as bleeding and reperfusion injury (J. Nucl. Med., 41, 1409 (2000) or poor therapeutic effect, etc. would result when administered long after the occurrence of ischemia.
On the other hand, astrocyte function-improving agents have an activity for ameliorating neurological symptoms even quite a long time (24 to 48 hours) after the occurrence of ischemia, but they do not have a thrombolytic activity.
The astrocyte function-improving agents are disclosed, for example, in Japanese Patent Unexamined Publication No. H07-316092 (U.S. Pat. No. 6,201,021), wherein a compound represented by the formula (I):

wherein R6 is hydroxy, C1-4 alkoxy, C1-4 alkoxy substituted by one phenyl group, or NR9R10 
in which R9 and R10 are independently    (i) hydrogen,    (ii) C1-4 alkyl,    (iii) phenyl,    (iv) phenyl substituted by C1-4 alkoxy or carboxy,    (v) 4- to 7-membered heterocycle comprising one nitrogen atom,    (vi) C1-4 alkyl substituted by (a) phenyl, (b) phenyl substituted by C1-4 alkoxy or carboxyl or (c) 4- to 7-membered heterocycle comprising one nitrogen atom,    (vii) 4- to 7-membered heterocycle comprising one or two nitrogen atoms or 4- to 7-membered heterocycle comprising one nitrogen atom and one oxygen atom, when taken together with the nitrogen atom bonded to R9 and R10, or    (viii) amino acid residue, when taken together with the nitrogen atom bonded to R9 and R10;
n, R11 and R5 are
(1) n is 1;
R11 is hydrogen;
R5 is (C1-10 alkyl of which one carbon atom is substituted by one to three fluorine atom)-CH2—, wherein R5 does not represent F—(CH2)5—, F—(CH2)6—, F—(CH2)7— or F3C—(CH2)2—, or
(2) n is 0 or 1;
R11 is hydrogen or chlorine;
R5 is:                C3-10 alkyl,        C3-10 alkenyl,        C2-10 alkoxy,        C2-10 alkylthio,        C3-7 cycloalkyl,        phenyl,        phenoxy,        F—(CH2)m— (wherein m is an integer of 5 to 7),        F3C—(CH2)2—, (C2-10 alkyl substituted by one or two chlorine atom)-CH2—,        (C1-5 alkyl substituted by one or two substituents selected from the group consisting of C1-4 alkoxy, C3-7 cycloalkyl, phenyl and phenoxy)-CH2—; or        
R5 and R11, taken together, are C3-10 alkylidene,
is described to possess an activity of improving brain function (especially improvement in astrocyte function) and is useful for the treatment and prevention of Alzheimer's disease, amyotrophic lateral sclerosis, progressive supranuclear palsy, olive-ponto-cerebellar atrophy, neuronal dysfunction by cerebral stroke and traumatic brain injury, multiple sclerosis, astrocytoma, meningitis, brain tumor, Creutzfeldt-Jacob disease, AIDS dementia and the like.
The astrocyte function-improving agent refers to a medicine which is useful for the treatment of diseases resulting from neuron damages by a factor which is released when astrocyte is activated for some reasons. Such an agent has activity for recovering activated astrocyte into normal astrocyte as well as suppressing the activation of astrocyte.